Such measuring systems are known per se.
Such measuring systems include an x-ray tube for emitting x-rays along a first geometric longitudinal axis, a proportional counter tube for receiving radiation backscatterred from the measurement object, and a carrier for supporting the measurement object and for bringing the measurement object into the geometric longitudinal axis. See, for example, DE-PS 3,239,379. There are, however, also measuring systems which are larger in terms of size and which are fully encased for reasons associated with radiation protection. These then include, for example, the device according to FIG. 1 of the prior art in a relatively large container.
In this case, of course, the positioning of the measurement object on the carrier presents difficulties. In order to see from outside where the measurement object is situated, use has been made of expensive devices with very many complicated optical elements. For example, a camera has been used, which had a chip i.e. an image converter as used in video cameras, which is also known as a Charge Coupled Device (CCD), and the camera was connected by leads to a video viewing screen. In addition, some illuminating means were provided in the measurement space, so that it also became warm in the measurement region; this damages the proportional counter tube. Furthermore, the attempt to operate using cold light sources only shifts the problem, since these again involve an additional expenditure.